1. Field of the Invention
The invention relates to a tire module for sensing wheel state variables and/or tire state variables and to a method for sensing wheel state variables and/or tire state variables.
2. Description of the Related Art
In modern motor vehicles, tire air pressure-monitoring systems are being increasingly used to avoid defects or accidents which are due to incorrect air pressure in the tires. These conventional systems usually include direct or indirect sensing of the air pressure.
However, in particular for the safety and the durability of a tire it is not the air pressure in the tire which is decisive but rather the length of the tire contact area (also referred to as the tire contact length). The (central) tire contact length of a tire is a decisive variable for the state of the tire or of the wheel.
WO 2005/056311 A2 discloses a sensor transponder and a method for measuring the length of the tire contact area and the wheel load. In one embodiment, the transponder, which comprises an acceleration sensor, is attached to the inside of a tire, opposite the tire tread. The acceleration can be measured according to a capacitive, piezoresistive, ferroelectric, electrodynamic or else piezoelectric principle. The time profile of the acceleration is sensed by means of the acceleration sensor and evaluated in a complex fashion in order to obtain the tire contact length.